I know a lot of people were not happy with the search functionality from Amazon being added to Ubuntu but I was really pleased with it till now -- it stopped working. Since upgrading to 13.04 I am no longer able to search for products using the Dash. Did that feature get canned?
You should know that this feature has not been disabled, it didn't stop to work, it is still installed and ready to use by default on Raring Ringtail.
So you should have a problem with your internet connection or with the specific package.